8 free tools
Energy & Electricity calculators
Electricity cost, electric bills, solar panels and payback, EV charging, generators and battery backup. Each tool shows the formula, worked examples and sources.
Energy & ElectricityBattery Backup CalculatorHow long a battery bank will run a load, and how big a battery you need for a set number of hours, for lead-acid and lithium batteries.Energy & ElectricityElectric Bill CalculatorEstimate your monthly electric bill from the appliances you use, with a breakdown of which ones cost the most.Energy & ElectricityElectricity Cost CalculatorHow much it costs to run any appliance per hour, day, month and year, from its watts, hours of use and your price per kWh.Energy & ElectricityEV Charging Cost CalculatorCost and time to charge an electric car at home or in public, cost per mile or km, and monthly savings compared with a gas car.Energy & ElectricityGenerator Size CalculatorFind the generator size you need from the running and starting watts of the appliances you want to power, with a safety margin.Energy & ElectricitySolar Panel CalculatorHow many solar panels you need and what system size, from your electricity use, peak sun hours, panel wattage and system losses.Energy & ElectricitySolar Payback CalculatorSolar panel payback period, yearly savings and long-term return from system cost, incentives, production, self-use, export credit and rising electricity prices.Energy & ElectricityWatts to Amps CalculatorConvert watts to amps and amps to watts for 12 V DC, 120 V, 230 V and 240 V single-phase and three-phase circuits, with power factor.